1. if the temperature of a gas remains constant, then the pressure of the gas will increase if the a. mass of the gas molecules decreases. b. diffusion of the gas molecules increases. c. size of the container is decreased. d. number of gas molecules in the container is decreased. 2. when gay-lussac’s law of combining volumes holds, which of the following can be expressed in ratios of small whole numbers? a. pressures before and after reaction b. volumes of gaseous reactants and products c. kelvin temperatures d. molar masses of products and molar masses of reactants 3. equal volumes of ideal gases at the same temperature and pressure contain equal numbers of a. protons. b. ions. c. particles. d. electrons. 4. at constant temperature and pressure, the volume of a gas is directly proportional to its a. molar mass. b. number of moles. c. density at stp. d. rate of diffusion. 5. to use the ideal gas law to d

These are four questions, each with its complete answer.

Question 1. If the temperature of a gas remains constant, then the pressure of the gas will increase if the a. mass of the gas molecules decreases. b. diffusion of the gas molecules increases. c. size of the container is decreased. d. number of gas molecules in the container is decreased.

Option c. the size of the container is decreased.

Explanation:

At constant temperature, the pressure of a gas has the following relations with other variables:

Amount of gas: direct proportion, the greater the amount of particles of the gas, molecules or atoms, the greater the pressure of the gas.

       Then, as long as the number of molecules in the gas does not change, a decrease in the mass of the gas molecules (option a) does not modify the pressure, which makes that the option a. is not valid.

       Option b, diffusion of the gas molecules increases, means that some molecules will abandon the container. So, following the direct proportion of the pressure with the number of molecules, this option means a decrease of the pressure, and you discard it.

       Following the same reasoning, the option d, number of gas molceules in the container is decreased, also means a decrease of the pressure, and this option is discarded.

Volume: as per Boyle's law, the volume and the pressure of a gas are in inversed relation. Then, the option c., size of the container is decreased, indeed means the increase of the pressure, and this is the correct option.

Question 2. When Gay-Lussac’s law of combining volumes holds, which of the following can be expressed in ratios of small whole numbers? a. pressures before and after reaction b. volumes of gaseous reactants and products c. kelvin temperatures d. molar masses of products and molar masses of reactants

option b. volumes of gaseous reactants and products

Explanation:

Gay-Lussac’s law of combning volumes states that, at constant temperature and pressure, when gases combine the volumes are in the ratio of simple whole numbers.

Hence, it is not pressures before and after reaction (option a), kelvin temperatures (option c), or molar masses of products and molar masses of reactants (option d) what holds.

It is volumes of gaseous reactants and products (option b) what holds.

Question 3. Equal volumes of ideal gases at the same temperature and pressure contain equal numbers of a. protons. b. ions. c. particles. d. electrons.

option c. particles.

Explanation:

This is a direct deduction from Avogadro's principle: no matter the size of the particles, either single atoms, or small or large molecules, at the same temperature and pressure, equal volume of gases contain the same number of particles (atoms or molecules).

That is why it is stated that at 1 atm and 0°C, the volume of 1 mole of any gas is approximately 22.4 liter.

Question 4. At constant temperature and pressure, the volume of a gas is directly proportional to its a. molar mass. b. number of moles. c. density at STP. d. rate of diffusion.

option b. number of moles.

Explanation:

As explained on the answer to the question 4, Avogadro's law states that at constant temperature and pressure, the volume of a gas is directly proportional to its number of particles.

Moles is a unit of amount of particles. One mole is equal to 6.022 × 10²³ particles (atoms or moles, in the case of gases).

You can also reason from the ideal gas equation:

pV = nRT ⇒ n = (pV) / (RT) = V (p / RT)Then, since (p / RT) is constant, p is directly proportional to V.

Ais the correct answer

The answer is c) pyrite